The Solar-Terrestrial Environment and Climate Unit investigates the mechanisms behind long-term variations in solar activity on centennial and longer timescales through the analysis of cosmic-ray-induced isotopes, such as carbon-14 in tree rings, and beryllium-10 in ice cores and carbonate sediments. These isotopes also provide the records of past extreme solar flares, offering fundamental insights into their characteristics.
Realizing the ability to predict solar activity is vital for our society, as variations in solar activity are one of the key drivers of temporal fluctuations in climate and weather patterns. The timescales of solar variations range from one month to a few thousand years. Observational records have shown that climate and meteorological phenomena often exhibit periodic variations in sync with those of the Sun; however, the mechanisms underlying this connection remain unresolved. In addition to visible and UV radiation from the Sun, charged particles originating from outside the heliosphere and modulated by solar wind are suggested to influence climate and weather, potentially by altering cloud properties. Our unit aims to address this issue by using diverse datasets and numerical simulations to achieve a comprehensive understanding of the Earth as a system open to the surrounding space environment.
